The present invention relates to an image display panel and an image viewer of an image display apparatus which uses liquid crystals or organic light-emitting diodes and which can be manufactured at low cost.
The conventional art will be described hereafter with reference to FIG. 7.
FIG. 7 is a schematic diagram of an image display panel 150 using, for example, a low-temperature polycrystalline Si-TFT liquid crystal in accordance with a conventional example. In an image region 105, pixels 100 each having a liquid crystal capacitance 102 and a pixel switch 101 constituted by a low-temperature polycrystalline Si-TFT are arranged in matrix form, and the gate of the pixel switch 101 is connected to a gate-line shift register 106 via a gate line 103. In addition, the drain of the pixel switch 101 is connected to a D/A converter 107 via a signal line 104. An output signal from a latch circuit 108 is inputted to the D/A converter 107, and an output signal from a horizontal shift register 109 is inputted to the latch circuit 108. Signals from a gate-line shift register input terminal 121, a latch circuit input terminal 122, and a horizontal shift register input terminal 123 are inputted to the gate-line shift register 106, the latch circuit 108, and the horixontal shift register 109 via level shift circuits 111, respectively. In addition, high voltages supplied from a high-voltage input terminal 124 are applied to the respective level shift circuits 111. The level shift circuits 111 are circuits for boosting a low-voltage signal of, for example, 5 V or less inputted to the input terminals 121 to 123 to a high voltage of, for example, 13 V necessary for the operation of the registers 106 and 109 and the latch circuit 108. In addition, a signal line from an image signal data input terminal 125 is connected to the latch circuit 108. The aforementioned elements are configured on an insulating substrate such as a glass substrate. It should be noted that a description will be omitted here of general arrangements necessary for an image display apparatus other than the image display panel 150, such as color filters, peripheral drive circuits, and the like.
Hereafter, a description will be given of the operation of the above-described conventional example. A horizontal shift signal, inputted from the horizontal shift register input terminal 123 and converted by the level shift circuit 111 to a high-voltage amplitude signal corresponding to a high voltage supplied from the high-voltage input terminal 124, drives the horizontal shift register 109. The horizontal shift register 109 drives the latch circuit 108 at a predetermined timing so as to allow a first latch circuit in the latch circuit 108 to consecutively latch image signals inputted from the image signal data input terminal 125. When the image signals corresponding to the number of pixels of one horizontal line are latched by the first latch circuit in the latch circuit 108, a latch signal inputted from the latch circuit input terminal 122 and converted to a high-voltage amplitude signal by the level shift circuit 111 is inputted to the latch circuit 108 so as to allow the image signals in the aforementioned first latch circuit to be latched by a second latch circuit in the latch circuit 108. Subsequently, the image signals corresponding to the number of pixels of one horizontal line and latched by the second latch circuit are inputted in parallel to the D/A converter 107 and subjected to digital-to-analog conversion, and analog image signal voltages are outputted to the signal line 104. At this time, a gate line drive signal inputted from the gate-line shift register input terminal 121 and converted to a high-voltage amplitude signal by the level shift circuit 111 drives the gate-line shift register 106 at a predetermined timing so as to turn on the pixel switches 101 of the pixels of a predetermined row through the gate line 103. As a result, the analog image signal voltages outputted to the signal line 104 is written in the liquid crystal capacitances 102 of the pixels of the predetermined row. The liquid crystal capacitances 102 are respectively provided with counter electrodes, thereby making it possible to display an image corresponding to analog image signal voltages which are applied to the liquid crystals of the respective pixels 100.
It should be noted that, concerning the above-described conventional art, a detailed description is given in, for example, ISSCC 2000, Digest of Technical Papers, pp. 188-189.
According to the above-described conventional art, by providing the level shift circuits 111 on the insulating substrate, signals which are inputted to the respective terminals of the gate-line shift register input terminal 121, the latch circuit input terminal 122, the horizontal shift register input terminal 123, and the image signal data input terminal 125 can be set to low-voltage amplitude signals of 5 V or thereabouts.
However, with the above-described conventional art, it has been impossible to configure all the circuits for driving the image display panel 150 by only low-voltage circuits of 5 V or less which can be coped with by a general LSI. The reason for this is that to apply a high voltage of 13 V to the level shift circuits 111, it is necessary to supply a high voltage of 13 V to the high-voltage input terminal 124 from an external circuit, so that it has been inevitable to provide a high-voltage power supply circuit in a peripheral device which is different from the image display panel 150 and which is provided in the image display apparatus to drive the image display panel 150. Since a high-withstand-voltage component other than a general LSI needs to be adopted for this high-voltage power supply circuit, it is difficult to configure the entire above-mentioned peripheral device by a general low-withstand-voltage LSI, which has resulted in an increase of the manufacturing cost of the image display apparatus.
An object of the present invention is to lower the cost of the image display apparatus by realizing all the circuits such as drive circuits and the like in the peripheral device by a general LSI having a low withstand voltage of 5 V or less.
The following means is adopted in the present invention to overcome the above-described problem.
An image display panel comprising an image region 105 in which pixels are arranged in matrix form, a gate-line shift register 106, a D/a converter 107, a latch circuit 108, a horixontal shift register 109, and a plurality of level shift circuits 111, wherein signals are inputted to said shift registers 106, 109 and said latch circuit 108 from a gate-line shift register input terminal 121, a latch circuit input terminal 122, and a horizontal shift register input terminal 123 through said level shift circuits 111, respectively, and a signal from an image signal data input terminal 125 is inputted to said latch circuit 108, all the elements mentioned being configured on an insulating substrate, characterized in that a high-voltage generating circuit 212 including a capacitance and a diode is provided on said insulating substrate, and that clocks having an amplitude of a low voltage and a predetermined frequency are inputted to said high-voltage generating circuit 212 from said high-voltage-generating-circuit input terminals 213, 214, while a low constant voltage is inputted to said high-voltage generating circuit 212 from a constant-voltage input terminal 215, so as to supply a high voltage to each of said level shift circuits 111 from an output terminal 216 of said high-voltage generating circuit 212.